DNA Structure/Organisation Flashcards
What are the ideas of nucleic acids?
They could be hereditary
What are the 3 types of bonds in DNA?
Hydrogen, Phosphodiester, Glycosidic
What are nucleosides?
Nucleotides without phosphate group
What does bacterial information indicate?
DNA as genetic information (Griffiths)
Describe the 2 strains of streptococcus pneumoniae
R strain benign (without protective capsule) so destroyed by immune system S strain (polysaccharide capsule) prevents detection by immune system so resistant
Describe Griffiths DNA experiment
Experiment shows when heat killed smooth cells and rough cells were combined, the heat killed cells cause the S cells to die and release its DNA contents which was taken up by R cells > Transforming R cells to S strained R cells > Now live R cells
Describe the DNA transforming principle experiment
Proved DNA was result of S strain causing R strain to become lethal/resistant
S cells appeared when there was no protein/RNA, means they’re not the cause of R cells becoming S cells. But when DNA wasn’t present, it caused R cells to become S cells
Describe the H-bonding between DNA bases
G forms 3 H-bonds with C
A forms 2 H-bonds with T
Describe the DNA packaging in eukaryotic cells
Single DNA runs length of each chromosome
1st chromosome of 23 pairs is largest (8cm), packed at mitotic metaphase into chromosome only 8um
Describe the levels of packaging in eukaryotic cells
DNA wraps around histones (proteins) to form nucleosome (10nm fiber) forms 30nm chromatin
What are the types of histones?
H2A, H2B, H3, H4 (X2) = Octamer (+ charged vs DNA - chg)
What is chromatin made up of?
Protein + DNA
What is euchromatin?
DNA available for transcription
What is heterochromatin?
Inactive DNA as its wrapped too tightly around histones so not expressed
